1. Field of the Invention
The present invention relates generally to cleaning and manufacturing. More specifically, the invention comprises bristle manufacturing. In particular, the invention provides a unique apparatus for forming bristles on a thin, pliable, substrate base or surface. Such bristles are envisioned as ideal for use on a finger mounted toothbrush.
In general, a first field of use of the disclosed invention is by professional and non-professional cleaning personnel. However, many other fields such as dental, medical, industrial manufacturing, transportation and home construction, could find potential uses for this invention.
2. Description of the Prior Art
There are a myriad of brushing devices currently on the market, including but not limited to hand brooms, industrial brooms, hand brushes, toothbrushes, floor polishers, automobile polishers, etc. In many of these brushing devices, individual strands or tufts of bristles are later attached to a separate rigid support surface. In prior manufacturing techniques, the synthetic resin bristles are first extruded (or natural hair bristles are used) and then glued or injection molded to a support surface such as a handle. These techniques are slow and costly, requiring placing the bristles in a specific location prior to filling a mold. The present invention overcomes these disadvantages by molding the bristles in-situ with a flexible support surface. In addition the present method is not only faster and therefore more economical, but also more accurate in that individual bristles are produced independently, and can be arranged in varying patterns, sizes, densities and heights. This results in a sculpted brushing surface that may be very complex in shape while being reproducible accurately and quickly.
My prior U.S. Pat. No. 5,107,562 issued to Dunn on Apr. 28, 1992 discloses a disposable finger-mounted toothbrush with holding means. The actual method of making this finger-mounted brush is not disclosed, and this patent is shown simply to illustrate one of the more beneficial areas of use for the method of the present invention. While finger-mounted toothbrushes have been known, the present method of attaching bristles to a thin surface is the only economically practical way known to the inventor to manufacture these type of brushes.
U.S. Pat. No. 5,108,814, issued to Harp et al. on Apr. 28, 1992, is directed to embossed oriented film. A thermoplastic film is introduced between a pair of rotating compression rolls using sufficient pressure to emboss at least one of the film surfaces. The method discussed is related to embossing as opposed to molding, and is incapable of producing bristle type appendages suitable for a brushing device.
A rotary molding apparatus and method is disclosed in U.S. Pat. No. 5,376,203, issued to Syme on Dec. 27, 1994. This method molds foam materials for use as carpet under padding. A sheet of a foamed material is pulled through a first set of rollers at a first rate followed by heating the material to decompose blowing agents thereby expanding the sheet. A second set of rollers then pulls the sheet at a second faster rate to stretch the expanded sheet so that it returns to its original thickness. Dimples or indentations on one of the rolls produces protrusions on one side of the sheet. As with the Harp et al. invention, this method is more closely related to embossing and is incapable of producing bristle type appendages suitable for brushing.
U.S. Pat. No. 5,476,563, issued to Nakata on Dec. 19, 1995 discusses a process of making a door mat. In the method, a large number of synthetic resin monofilaments are extruded between a first molding roller having concave grooves and a pattern forming roller having convex strips. This method produces a door mat with a surface layer and a reverse anti-slip surface layer formed by a large number of random, looped, synthetic resin monofilaments. This method does not actually produce the filaments and is incapable of producing non-looped bristle type appendages.
An apparatus and method for producing floor mats carrying flat tipped projections are shown in U.S. Pat. No. 5,554,333, issued to Fujiki on Sep. 10, 1996. A molding resin material is passed between a press roll and a mold roll. The mold roll is hollow and includes a number of through holes and an air venting means in the interior thereof. The through holes are filled with the resin material thereby forming the projections. The resulting floor mats, however, have projections that are relatively large and frustoconical in shape, making them impractical for use in brushing devices.
U.S. Pat. No. 5,688,538, issued to Barr et al. on Nov. 18, 1997 discloses an apparatus for three dimensional surface shaping of synthetic foam. The foam is compressed between a pattern roller and a smooth compression roller and is driven against a cutting edge. This results in a three dimensional pattern of arbitrary geometries including sharp edged flat surfaced geometric solids being produced on the foam surface. The apparatus is not suitable for producing long relatively narrow projections such as bristles.
A molding apparatus with a tuft feeder for making a brush is described in U.S. Pat. No. 5,728,408 issued to Boucherie on Mar. 17, 1998. The machine feeds preconstructed bristles to an injection mold for forming a brush head about tufts of the bristles. The method of making the bristles is not disclosed.
U.S. Pat. No. 5,792,408, issued to Akeno et al. on Aug. 11, 1998 is drawn to a molded surface fastener, and method and apparatus for manufacturing the same. In FIG. 14 a die wheel is shown with a multiplicity of engaging-element-forming cavities. Material is fed via an injection nozzle and fills the cavities. The engaging elements are then fed to heating and pressing means to finish forming the engaging elements. The engaging elements are designed to be engaged by loops in the mating fastener material, and as such are not suitable as brush bristles.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
The present invention includes a machine for producing bristles and a support surface for the bristles, the method by which the bristles and the support surface are produced and the bristles and support surface so produced. An extruder (or any device appropriate for pumping, forcing or otherwise feeding the type of material being used) feeds the material used to form the bristles and the support surface, from a supply source to an extrusion die. The material used can be any number of synthetic resins, plastics, etc. with varying densities and colors. A forming die in the shape of a drum is rotatably mounted proximate the extrusion die. The circumferential surface of the drum includes a plurality of recesses in the desired shapes and patterns. As the fluid material is extruded between the extrusion die and the forming die, the material fills the recesses in the drum that are facing the extrusion die. While the forming die disclosed herein is embodied as a rotating drum, other types of forming dies are envisioned such as a linearly moving plate or platen that includes recesses that are filled by the extruder.
While the material fills the recesses facing the extrusion die, the drum rotates to expose empty recesses and the filled recesses are rotated away from the extrusion die. In addition to filling the recesses, the fluid material fills a void formed by a wide shallow groove in the extrusion die. The depth of this groove thereby determines the thickness of the bristle support surface that is formed in-situ with the bristles. In the preferred embodiment, the groove is relatively shallow and a thin strip of material is formed as the support surface. The groove is also preferably wider than the distance between the outermost recesses, so that a portion of the flat support surface extends to either side of the bristles. This portion is useful both for attaching the bristles to other surfaces, as well as for handling the product in subsequent operations as is discussed below. Depending on the size and shape of the groove and recesses, the machine may have to index by stopping or changing the speed the drum or die as it passes the extrusion die to fill different areas at varying rates.
As the filled recesses are rotated away from the extrusion die, the material in the recesses cools and solidifies. Pressurized air is directed at a point where the bristles are released from the recesses in the drum. The pressurized air aids in this release as well as further cooling the material. Alternatively, other methods of assisting in the removal of the material may be used such as incorporating vents at the ends of the recesses. The vents would allow air to escape as material fills the recesses, and pressurized air or fluid could be forced through the vents to remove and cool the solidified material. Two pairs of drive wheels (one pair for each side) grip the support surface that extends on either side of the outermost bristles (as described above) to feed the finished product to further manufacturing processes such as cutting, attachment to brushing devices, etc. These further processes are well known industrial processes and shall therefore not be further described.
A significant advantage of the present invention, is the ease with which the extrusion die and the forming die or drum can be replaced. Dies of different thickness can be used for different widths of the finished brushing device. Forming dies can be contemplated having recesses in a wide variety of shapes, sizes, patterns, densities, etc., to produce whatever pattern and bristle shape is most suitable to the type of brush being manufactured. In addition to bristles, the recesses may be continuous straight or tortuous grooves for forming projections that can be used in squeegees, wiper blades, weather stripping, or other applications.
Accordingly, it is the primary object of the invention to provide an apparatus and method for producing bristles in-situ on a bristle support surface.
Another object of the invention is to provide a relatively thin bristle support surface with bristles thereon for attachment to a brushing device.
An additional object of the invention is to minimize complexity, cost and time required to fabricate a myriad of brushing devices.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.